This invention relates to mechanical manipulators and will be disclosed in connection with an improved remotely operable articulated cantilevered wrist manipulator. Mechanical manipulators are of ancient origin and have been utilized in a wide variety of applications including handling of explosives or other dangerous materials and performing work tasks in unsafe or undesirable working areas, as for example radioactive or underwater environments. More recently, and particularly since the embarkment of computer controlled industrial equipment, manipulators have been increasingly used to perform unsafe and undesirable tasks previously performed by humans with resultant cost savings and increased production efficiency. This increased use may be partially explained by dramatic improvements in control systems within recent years. These improved controls enhance the exploitation of the manipulator's potential as a general purpose machine and give the manipulator the ability and flexibility to perform a wide range of work tasks. Present day controls permit "pre-programmed input" information, usually coded in numerical form, on punched tape or magnetic storage, to instruct the machine through a series of complex movements needed to perform a particular task. The tapes for these control systems can then be easily stored and reinserted into the machine when it becomes necessary to perform the particular task again. The expensive and time-consuming set up time for the controlled machine is then eliminated once the tape is generated; and the machine may be designated as a general purpose machine capable of performing a wide variety of work tasks. The growing interest in general purpose automated manufacturing equipment suggests that the trend for the future is toward even further proliferation of the computer controlled industrialized manipulators or industrial robots.
The prior art robots are generally variations of three different type designs. One of these designs is the link and pivot design. This design employs a series of pivotally supported segments with an end-effector, as for example a grasping device or a welding gun, attached to one end. A second type has extending links in combination with pivots wherein the end points of the links translate along the axes of the links relative to each other. A third type of robot design is that employed by U.S. Pat. Nos. 3,922,930 and 3,739,923 which utilize a plurality of serially connected rotatable drive shafts to provide two or more axes of pivotal motion at a common point capable of being remotely operated. It is this latter type of design to which the present invention is directed.
Implicit in the concept of general purpose automated manufacturing equipment is a requirement of flexability. Indeed, as applied to industrial robots and particularly to those robots which are designed to be controlled by programmable computers, the requirement of flexability is of central importance. It is this characteristic, more than any other, which distinguishes the programmable robot from a dedicated machine capable of performing only a limited predetermined repetitive function. The flexibility offered by a programmable industrial robot is dependent upon both programming for the computers and the orientational and positional capability of the robot arm. More particularly, it is dependent upon the positioning and orientation of the end-effector attached to the end of that robot arm. This flexibility is enhanced by improving either the orientational capabilities of the robot arm or increasing the range of movement of the end-effector.
The instant invention utilizes a wrist section of the robot arm generally of the type disclosed in the above-mentioned patents, but makes important improvements, over these prior art devices which retain virtually all of the previous advantages while increasing both the orientational and positional capabilities. It increases the robot's flexibility and makes it more suitable as a general purpose automated apparatus.
The invention's unique organizational and positional arrangement of drive members permits three serially connected rotary shafts with axes intersecting at a single point to undergo continuous "rolls". The continuous "rolls", rotation about axes parallel to the shaft members, is possible as the arrangement voids the mechanical interference inherent in prior art devices. This advantageous situation is coupled with the capability of orientating the third, or most remote shaft, about a single point, achieved by making all of three shafts intersect at a single point.
The present invention, like most prior art manipulators, generates an imaginery spherical sector as it is rotated through space. It is capable of orientating a part normal to any point on the generated spherical sector. This capability thus eliminates "holes" or "voids" in the spacial orientation of the end-effector and increases the manipulator's flexibility.